Detection of special nuclear material and other contraband by prompt and/or delayed signatures from photofission

a technology of photofission and detection applied in nuclear radiation detection, radiation measurement, instruments, etc., can solve the problems of more difficult shielding of special nuclear materials, conventional explosives, chemical agents, drugs, etc., and achieve the effect of decreasing the detection of background radiation

Inactive Publication Date: 2018-04-10
VAREX IMAGING CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0009]In accordance with embodiments of the invention, at least the potential presence of Special Nuclear Material (“SNM”) is determined by the detection of prompt neutrons, prompt gamma rays, delayed neutrons, and / or delayed gamma rays from photofission, via time-of-flight (“TOF”) spectroscopic methods. The use of one or more TOF spectra enables separate detection of any or all of these photofission by-products, while decreasing the detection of background radiation that could interfere with proper identification of the by-products. In certain embodiments of the invention, the collection of prompt and / or delayed gamma rays, and / or prompt and / or delayed neutrons enables identification of the SNM present, as well as the presence of conventional explosives, chemical agents, and drugs, based on the unique signatures (energies) of emissions from respective excited nuclei of particular elements. The TOF data may also enable localization of materials in the container. The multiple modes of examination make it more difficult to shield SNMs, conventional explosives, chemical agents, and drugs, for example, from detection.

Problems solved by technology

The multiple modes of examination make it more difficult to shield SNMs, conventional explosives, chemical agents, and drugs, for example, from detection.

Method used

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  • Detection of special nuclear material and other contraband by prompt and/or delayed signatures from photofission
  • Detection of special nuclear material and other contraband by prompt and/or delayed signatures from photofission
  • Detection of special nuclear material and other contraband by prompt and/or delayed signatures from photofission

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second embodiment

[0087]In accordance with the invention, the at least potential presence of explosives, drugs, and certain chemical and biological agents, as well as SNMs, may be determined. In this embodiment, neutron scanning is used along with X-ray scanning to determine the elemental content of the cargo container 107 or other such object. Since neutrons have a cross-section 7 to 8 times greater than photons, they are more likely to cause fission in an SNM 114 in the cargo container 107.

[0088]FIG. 5 is a schematic representation of an example of a neutron / X-ray source 200 for use in this embodiment of the invention, comprising a linear accelerator 202. The linear accelerator 202 comprises an accelerating chamber 204 comprising a plurality of acceleration chambers (not shown), an electron gun 206, and an RF power supply 208, as in the radiation source 102. A headend 210 is shown including a drift tube 212 at the output of the acceleration chamber 202, to receive accelerated charged particles, suc...

first embodiment

[0091]In accordance with this embodiment, X-ray scanning is performed with the second target 216 in its first position away from the first target 214. The X-ray scanning with the first target 214 may be performed as described above with respect to the first embodiment to detect prompt and / or delayed gamma rays and neutrons, which are indicative of the presence of SNMs, and / or conventional X-ray scanning may be performed.

[0092]After sufficient data is collected, the second target 216 is moved into its second position behind the first target 214. A suitable time of flight spectrum to control the detectors as in the examples above may be developed, with longer time periods to detect photofission by-products resulting from the impact of neutrons on SNM or other materials, based on the distances between the radiation source 200, the cargo container 107, and the detectors 109, 110, 112. Some X-ray radiation may pass through the second target 216 without causing generation of neutrons, and...

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Abstract

In accordance with embodiments of the invention, at least the potential presence of Special Nuclear Material (“SNM”) is determined by the detection of prompt neutrons, prompt gamma rays, delayed neutrons, and / or delayed gamma rays from photofission, via time-of-flight (“TOF”) spectroscopic methods. Methods and systems are disclosed.

Description

FIELD OF THE INVENTION[0001]Radiation scanning of objects and, more particularly, radiation scanning of objects for Special Nuclear Material and other contraband based on the detection of prompt and / or delayed gamma rays and neutrons.BACKGROUND OF THE INVENTION[0002]High energy (MeV) X-ray radiation is used to scan cargo containers and air shipments for contraband, verification of manifests for customs, and duty collection. The items of concern may depend on the individual customs agencies for a country, or individual ports. X-ray radiation may be used to non-intrusively examine cargo containers and other objects for illegal drugs, weapons, explosives, chemical agents, and / or biological agents. Radioactive, fissionable, fissile, and fertile materials, including Special Nuclear Material (“SNM”) that may be used to manufacture atomic devices, including dirty bombs, may also be smuggled in such objects.[0003]Fissile materials, such as uranium-235, uranium-233, and plutonium-239, may un...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): G01T3/00G01V5/00
CPCG01V5/0091G01T3/005
Inventor CLAYTON, JAMESSEPPI, EDWARD J.
Owner VAREX IMAGING CORP
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